Definitions: partly paid shares
A partly paid share is a share which is issued for an amount below its par value. For example, a £1 share may be issued partly paid at 60p. The company can then ask the shareholder to pay up the 40p difference between the subscription price and the par value of £1 at some time in the future after the share is issued.
Normally, a partly paid share would not be regarded as being of the same class as a similar share which was acquired fully paid. You may, however, treat partly paid shares as being of the same class as fully paid shares provided the balance of the subscription price is payable within six months of the issue of the shares. This practice applies both to shares received as partly-paid under rights issues and to purchases of partly-paid shares in the market.
If a public company issues partly paid shares the terms of issue will normally specify that the full price be paid by fixed instalments within a relatively short period of time.